There are known air conditioning apparatuses as apparatuses for controlling temperature, humidity, or a degree of pollution of air in a room. In the air conditioning apparatuses, the air in the room is taken into an inside of the apparatus, a physical property of the air taken in the apparatus is changed into a desired state, and the air is blown to an outside of the apparatus. Particularly, the air conditioning apparatus having an air cleaning function for improving the degree of pollution of the air in the room receives attention with a recent change in living environments.
Conventionally air cleaners having a dust trapping function and a deodorization function have been widespread. Furthermore, in addition to these functions, air cleaners having an antibacterial or bacteria elimination function against physically-harmful airborne bacteria are becoming common in recent years. As used herein, the “antibacterial function” shall mean that growth of the bacteria adhering to a fibrous filter is suppressed, and the “bacteria elimination function” shall mean that microorganisms are killed to decrease an absolute number thereof.
In such air cleaners, the dust trapping function, the deodorization function, and the antibacterial function are exerted by various filters disposed in an air flow path. Generally, the air cleaner includes a duct filter having the dust trapping function and a deodorization filter having the deodorization function as the various filters. The trapping filter traps the dust in the air. The deodorization filter traps and decomposes an odor component in the air. The bacterial filter controls or eliminates the physically-harmful airborne bacteria.
For example, Japanese Patent Laying-Open No. 11-114333 (Patent Document 1) discloses a deodorization filter including a powder activated carbon deodorization portion and a granular activated carbon deodorization portion. Japanese Patent Laying-Open No. 9-239229 (Patent Document 2) discloses a humidity conditioning tool containing wood charcoal and zeolite. Japanese Patent Laying-Open No. 2002-58729 (Patent Document 3) discloses a deodorization filter including an activated carbon layer and a nonwoven layer.
Recently, awareness of an indoor environment is increasingly raised. Even in the air cleaner, a function of decomposing and removing a physically-harmful substance is demanded in addition to the dust trapping function, the deodorization function, and the antibacterial function. Examples of the physically-harmful substance include a VOC gas (Volatile Organic Compound) such as toluene and formaldehyde and carbon monoxide contained in cigarette smoke.
As to a filter having the function of decomposing and removing the physically-harmful substance, for example, Japanese Patent Laying-Open No. 10-235129 (Patent Document 4) discloses a filter containing an aldehyde removing chemical agent, a nitrogen-system substance removing chemical agent, and a sulfur-system chemical agent.    Patent Document 1: Japanese Patent Laying-Open No. 11-114333    Patent Document 2: Japanese Patent Laying-Open No. 9-239229    Patent Document 3: Japanese Patent Laying-Open No. 2002-58729    Patent Document 4: Japanese Patent Laying-Open No. 10-235129